War simulation in 1999 pointed out Iraq invasion problems

A series of secret U.S. war games in 1999 showed that an invasion and post-war administration of Iraq would require 400,000 troops, nearly three times the number there now.And even then, the games showed, the country still had a chance of dissolving into chaos.

In the simulation, called Desert Crossing, 70 military, diplomatic and intelligence participants concluded the high troop levels would be needed to keep order, seal borders and take care of other security needs.

The documents came to light Saturday through a Freedom of Information Act request by George Washington University's National Security Archive, an independent research institute and library.

"The conventional wisdom is the U.S. mistake in Iraq was not enough troops," said Thomas Blanton, the archive's director. "But the Desert Crossing war game in 1999 suggests we would have ended up with a failed state even with 400,000 troops on the ground." - cnn
There are about 144,000 U.S. troops in Iraq, down from a peak in January of about 160,000.

A week after the invasion, in March 2003, the Pentagon said there were 250,000 U.S. ground force troops inside Iraq, along with 40,000 coalition force troops.